Many roadways are now monitored by video cameras. While a video camera providing a live feed to an operator has many benefits, such as allowing the operator to observe and quickly respond to changing traffic conditions without having to be physically present at the site, such systems are expensive. Government and private roadway authorities must make the most use of the resources provided. While the benefit of camera monitoring is well known, spending limited resources on the physical roadway often takes priority.
In order to gain the most use of the monitoring infrastructure, many cameras are pan-tilt-zoom (PTZ) mounted to provide operators the ability to target sections of the roadway. If the camera has been calibrated, such that the image can be accurately translated into vehicle metrics (e.g., speed and position), any movement requires recalibration to maintain accurate metrics. While fixed cameras may need only occasional calibration, they are obviously limited to fixed viewing applications.
Many factors make calibration difficult. If a camera is calibrated in one PTZ setting then returning the camera to that same PTZ setting would calibrate the image. However, many PTZ mounts are not precise enough to ensure an accurate return to the PTZ setting. For cameras with a precise PTZ mount, returning to the same PTZ setting means the camera cannot gather reliable traffic metrics while the camera is outside of the calibrated PTZ setting.
Other calibration systems require an operator to manually inform the camera system of a known measurement. Such systems require an operator to, for example, draw a line or box and inform the system of the actual dimension of the line or box. Improvements to such manual systems utilize machine recognition systems to identify landmarks associated with a known distance, for example, the distance between streetlights or lane delineation marks. However, even with such systems calibration can be difficult if the view of the landmark is obstructed, such as when lane markers are obscured by snow, gridlocked traffic, or sun glare. Resurfacing the roadway may cause such systems be unable to calibrate for extensive periods of time.
It is with respect to these and other considerations that the present invention has been developed. However, the present invention is not limited to solving the particular problems indicated above.